1. Field of the Invention
The invention relates to a pump apparatus for various fluid devices, for example a fluid pressure power steering apparatus. Especially, the invention relates to a bypass path, formed between a flow control valve and a suction portion of the pump apparatus, and a dividing wall formed opposite to an end portion of the bypass path to suck operation fluid.
2. Description of the Related Art
It is typically known a vane pump apparatus for a fluid pump apparatus using for a fluid pressure power steering apparatus. A vane pump apparatus is, for example, disclosed in the U.S. Pat. No. 6,299,418. The typically known vane pump apparatus has a flow control valve 10 to return as excess fluid to the pump a part of discharged fluid from a pump unit discharging operation fluid to the power steering apparatus in order to send constant volume of operation fluid to the power steering apparatus. Such flow control valve is disclosed in Japanese Utility Model laid-open publication No.05-096483 and said U.S. Pat. No. 6,299,418.
The typically known vane pump apparatus is shown in FIG. 1. A vane pump apparatus includes a bypass path 30 between a flow control valve and a suction portion of the pump apparatus to be communicated with suction paths 20, 20′ of a path for the suction portion. Excess fluid is flowing into the bypass path. Adjacent to a connecting portion of the bypass path 30 to the flow control valve 10 is formed an opening portion 90 of a reservoir path communicated with a reservoir. The bypass path 30 is at its end portion to be connected with left and right suction paths 20, 20′. Operation fluid discharged from a pump unit is introduced through an introducing path 50 to the flow control valve 10. A part of said operation fluid controlled by the flow control valve 10 is discharged as excess fluid from a bypass hole 310 through a clearance formed at a head of a spool 150. A direction of the discharged excess flow is in a deviated slanting way shown in FIG. 1 because of a retracting direction of the spool 150 and a position of the introducing path 50. In recent year, the vane pump apparatus is needed to discharge larger volume of said fluid in higher pressure so that excess fluid discharged in the deviated slanting way acts more strongly against the bypass path 30. A side wall 330 of the bypass path 30 in a direction of the deviated slanting way is able to receive damages by discharged excess fluid. Relating to this damage, said Japanese Utility Model laid-open publication No.05-096483 or said U.S. Pat. No. 6,299,418 discloses a technology of an ellipse form of a cross section of the bypath path and the ellipse form has a wider length width than a breadth width. The technology reduces energy of said discharged fluid and thereby reduces damages of the side wall 330 of the bypass path 30.
In the typically known vane pump apparatus, as shown in FIG. 1, when said operation fluid flowing in the bypass path is divided into each of said suction paths 20, 20′, more operation fluid flow into the suction path 20 at a side in a deviated slanting way. This makes an un-equivalent volume of divided operation fluid in left and right suction paths to cause a generation of a vibration and a noise in an operation of the pump apparatus.